More than half of those arrested in the UK on suspicion of terrorism since September 2001 have been released without charge, according to figures.
An armed police officer outside Heathrow Airport
Home Office statistics show 669 of the 1,228 people arrested in terrorist investigations were later freed.
Some 224 have been convicted in terrorism-related trials, with 114 awaiting trial.
More than 130 people have been charged under terrorism laws, while 195 were charged with other criminal offences.
TERROR CHARGES 2001-2007
132 charged under terror laws
109 under terror and other laws
195 charged with other offences
Source: Home Office
Since 2001, some 436 people have been charged in relation to terrorism investigations. Almost 200 of these were under standard criminal offences such as conspiracy to murder.
Since September 2001, 76 of those arrested have been handed on to immigration authorities and 11 dealt with under mental health laws.
In the first three months of 2007, police charged 62 people in connection with terrorism investigations, 39 of them under specific terrorism offences.
KEY 2007 CONVICTIONS
30 April: Five men in fertiliser bomb plot
15 June: Seven men in Al-Qaeda linked plot
4 July: Three men involved inciting terrorism via the web
9 July: 21/7 suicide bombers
The figures, compiled by the Metropolitan Police's terrorism chief, reveal that 41 people have been convicted under the Terrorism Act and 183 under other legislation including murder, grievous bodily harm, firearms offences, fraud and false documents.
False papers and fraudulent fund-raising have both featured in recent trials of men involved in major terrorism conspiracies.
However, the figures do not include a list of recent convictions that have led to the jailing of some 19 men involved in major plots.
These convictions include the four men who carried bombs during the 21 July suicide attacks and five men in an international network planning to build a massive fertiliser bomb.
C-charge camera access
In a separate move, the Home Secretary has granted the Metropolitan Police permission to access in real-time London's massive congestion charge camera system.
The network, which electronically reads numbers plates and bills car owners, will be available to counter-terrorism officers.
Tracking suspects by CCTV is a key element of terrorism investigations - but it involves thousands of man hours of reviewing video to plot the movements of vehicles.
In a written ministerial statement Home Office minister Tony McNulty told the House of Commons that Transport for London and the Metropolitan Police would no longer be subject to parts of the Data Protection Act.
The law is designed to prevent personal information held on a computer by one body sharing it with another without good reason.
"The Commissioner of the Metropolitan Police believes that it is necessary due to the enduring, vehicle-borne terrorist threat to London," he said, adding that the service would produce an annual report for watchdogs on how it is using number plate information.